Update oauth-client-credentials.mdx

Author: pcarleton

specification/draft/oauth-client-credentials.mdx

@@ -58,7 +58,7 @@ Clients **MUST** authenticate using one of these methods:
 - Client Secret
   - Clients use a Client Secret transmitted in the request content as defined
     in
-    [OAuth 2.1 Section 2.4.1](https://www.ietf.org/archive/id/draft-ietf-oauth-v2-1-13.html#name-client-secret)
+    [OAuth 2.1 Section 4.2](https://www.ietf.org/archive/id/draft-ietf-oauth-v2-1-13.html#name-client-credentials-grant)
 
 ### Server Metadata Requirements